Portable air-compressor.



Specification of Letters Patent. Patented Jimmie no, llfllfim Application filed December lb, limit. Serial No. M73289.

To all whom it may concern V Be it known that we, Emvns'r ENIRY Him. and HAROLD HILL, subjects of England, re-

siding at 56 Broomhall street, Shefield, in v the county of York, 'England, have inveiited new and useful Tmprovements in Portable Air-Compressors, of which the following is a specification.

Our present invention is an improvement on or modification of the invention set forth in our specification of Britishlietters lPatent No. 27,507 of 1906, in which the object sought was to provide a light portable apparatus which when employedfor inflating a tire can be so used that the energy exerted over and above what is necessary to force the" air at a convenient velocity through the small orifice provided for the purpose, can be stored up and accumulated in a chamber forming an integral part of the apparatus, Thus when it is desired to inflate a tire, it will be found that owing to the resistance in forcing the air through the restricted orifice in the tire, the pressure in the compressor will accumulate until it becomes much higher than that which has been pumped into the tire, and when this accumulating volume has reached the maximum pressure which can be conveniently obtained, the operation of pumping can be briefly suspended while the compressed air stored up in the accumulator expands and flows through the orifice into the tire, until the pressures in the accumulator and the tire are equalized.

The pumping operation can then be resumed until the accumulator is again stored with air at a higher pressure than that contained in the tire, and so on until the desired maximum pressure has been attained, at which point it will be found that the force employed in pumping will be balanced by the pressure in the tire.

In the present invention the object to be attained is the same as in the previous patent, as set forth in the foregoing, statement, but the outer barrel is providedwith inlet valves (of any usual type) both at the top and bottom so that air is drawn in both at the up and the down stroke of the plunger in a manner similar to that adopted in several classes of air compressors as at present made. The air drawn in is subjected to three compressions before being delivered to the tire; and the general arrangement of the pump renders it capable of dealing with a larger volume of air and compressing it ina moretween them two packing leathers, d, d

efl'ective manner than was the case with the compressor made according to our previous invention above referred to.

Uur invention will be better understood on reference to the accompanying sheet of drawings, in which- Figure 1, illustrates a vertical sectional view of our improved air compressor as it would appear when the plunger is on the downstroke, and Fig. 2, is a similar part view showing the compressor as it would appear when the plunger is on the upstroke.

The same letters refer to similar parts in both. views. i In the form of air compressor to which our invention is applicable and as illustrated in the accompanying sheet of drawings, concentric barrels, a, a of, are employed the second or middle barrel a also serving as a plunger rod. The outer barrel, a, is provided with inlet valves, 6, and 6 at the top and bottom respectively; and the middle sliding barrel, a, which forms-the plunger rod has secured in its lower end a piston or plunger, 0, adapted to fit the bore of the outer barrel, a.- The last named plunger, 0,

.is made hollow and provided near its upper low plunger, c,above mentioned is made in two parts screwed together and holding beplaced back to back, which leathers are a sliding lit for the outside barrel, al- The interior of the hollow plunger, 0, contains a central flanged body 6 having a central hole, 0 through which the inner barrel, 0?, passes; the lower end of this flanged body is screwed into the base of the hollow plunger, 0. The circular portion above the flange of the body is encircled by a sleeve or valve proper, 7', which is made an easy fit so as to leave, an annular space, 7, between it and the portion that it surrounds. The lower edge of the hole in this sleeve or valve, f, is cut away so as to provide a clear passage to the annular space, f above referred to. The seat, 9, for this valve is rovided by a disk of leather or other suitab e material resting upon the flange of the body, 6. A packing leather, h, is held in place on the valve by a retaining ring, 713, and makes contact with the interior wall of the second barrel, ah. Air ports, 2', are-formed in the bottom of the plunger, 0, which communicate with the hollow interior containing the before described valve. In order to make the plunger, 0, a close fit upon the inner barrel, a which passes through it,

a gland, j, of any suitable form is arranged in the recessed lower portion of the valve body. v

Inside the middle barrel, a we place an inner barrel, 0?, which is screwed at its lower end into the base of the compressor and also passes through the center of the plunger, 0; the upper end of this inner barrel, a being provided with a cap, is, upon an extension of which is mounted a sliding valve and-pack- A of valve seat, is. The last named cap, 70,

and extension piece is formed with a central vertical orifice, on, leading to the interior of the inner barrel, a two or more cross ports, m are also formed leading into the orifice, m, which ports are opened or closed according to the position of the sliding valve, Z. The lower end of the orifice, m, in the cap is closed by means of a ball valve, n, held in place by a spring, a. i The bottom of this inner barrel communicates with the air discharge pipe or orifice,

The action of our improved air compressor is as follows: Assuming the plunger, 0, to be moving downward (as illustrated in Fig. 1) air is drawn into the outside barrel through the top inlet valve, 6; at the same time the air underneath the plunger, 0, is-

compressed and air passes through the ports, 11, in the bottom of the plunger, 0, lifts the sliding valve, f, passes through the annular space, f, between the valve and the valve body, andso into the middle barrel, a. When the plunger, 0, has reached the end of its downward strokeand the return stroke is commenced, (as shown in Fig; 2), the air on the top side of the plunger, 0, is compressed and thereupon opens-the ball-valve, 0 near the top edge of the plunger, allowing the air to pass directly into the middle barrel, a I At the same time the pressurein the middle barrel forces the sliding valve, f,

in the plunger, 0, on to its seat thereby cutting ofi' communication with that portion of the outside barrel, a, below the plunger. The ascent of the plunger compresses the air in the middle barrel thereby liftin the sliding valve, Z, mounted on the cap, of the inner barrel, a whereupon the air passes through the cross ports, m in the extension of the cap, and so into the upper part of the middle barrel, a When the upstroke is completed and the down stroke is again commenced, the air in the upper part of the middle barrel, 0, is compressed by the closed end of the middle, barrel and forces the sliding valve Z, on to its seat again and passes through the orifice, m, in the cap of the inner barrel and past the spring pressed ball valve, n, into the interior of said inner barrel, a. From this point it passes down the inner barrel to the delivery orifice, o, and so to the tire.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is I 1. In a portable air compressor comprised of three concentric barrels, the combination with the middle barrel a, of a hollow plunger 0, having within it a central flanged body 0' and central hole'e and screwed at its lower end into the base of said plunger; the upper portion of said body being encircled by a sleeve, f, fitted with a packing leather h, and retaining ring 71, and of a size and shape to provide an annular space 7, and in its closed position bearing upon'a seat g, substantiallyas herein described and illustrated on the accompanying drawings.

2. In a portable air compressor comprised of three concentric barrels, the combination with the inner barrel 0?, of a cap 70, and extension piece, having central vertical orifice m, cross ports m and stop is, sliding valve and packing leather Z forming a plunger within the interior of the middle barrel a, substantially as herein described and illustrated on the accompanying drawings.

In testimony whereof we have signed our names to this specification in'the presence of two subscribing witnesses.

ERNEST HENRY HILL. HAROLD HILL. Witnesses:

R. HEBER RAnFoRn, FRANK WALKER. 

